JPS5983238A - Position detector - Google Patents

Abstract

PURPOSE:To detect accurately a position, by taking out the output signal of a magnetic flux detecting means through a band pass filter to eliminate the influence of external magnetic fields such as a deflecting magnetic field of a cathode-ray tube. CONSTITUTION:Components, which are vertical to the plane of a position detecting plate 10, of the magnetic flux generated by flowing of a current to conductors X1, X2-Xn- or Y1, Y2-Ym- are detected by a magnetic flux detecting means 30. An output signal SS of the detecting means 30 is supplied to a band pass filter 51, and signal components of a low frequency due to the magnetic flux of external magnetic fields are eliminated during the horizontal scanning period of a jointly used cathode-ray tube. Therefore, only signal components of a high frequency which are generated by flowing of the current to conductors of the position detecting plate are obtained. Counting is performed from the time, when a certain current flows to the outermost conductor, to the time when the output of the band pass filter 51 crosses first a prescribed level in a prescribed direction. A position in the arrangement direction of plural conductors on the position detecting plate 10 of the magnetic flux detecting means 30 is detected by this counted data.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for sequentially detecting the position of the stylus on the tablet board when a figure is drawn with a stylus on a tablet board placed near a cathode ray tube. Data such as figures can be obtained by doing this, and this data can be used to display figures on the cathode ray tube, change the screen displayed on the cathode ray tube, or create or create the required figures. The present invention relates to a position detection device in a graphic display device or graphic creation device in a broad sense.

BACKGROUND TECHNOLOGY AND PROBLEMS As mentioned above, such a position detection device includes a position detection plate that constitutes a tablet plate disposed near the tracheal tube, and a position detection plate that constitutes the entire tablet plate. There are seven types of stylus used to draw shapes, etc.
The applicant has proposed the following magnetic position detection device.

This is because the position detection board that makes up the tablet board has multiple conductors arranged in parallel at regular intervals, and a constant current is applied to the multiple conductors at regular intervals in the order of the conductor arrangement. The stylus is configured with magnetic flux detection means that detects all of the magnetic flux generated when a current flows through the conductor wire and converts it into an electric signal. The positions of the plurality of conductive wires on the position detection plate constituting the tablet plate of the magnetic flux detection means are detected in the arrangement direction.

Specifically, the magnetic flux detection means is a coil, which is connected to the conductor I of the position detection plate.
vlli11 (A current flows due to electromagnetic induction due to the component of the magnetic flux generated by the current flowing in a direction perpendicular to the surface of the position detection plate. The magnitude of the magnetic flux component detected by this coil depends on the current flow. When a constant current is sequentially applied to a plurality of conductive wires in the order of the 24 wires at regular time intervals as a function of the position of the conductive wires relative to the magnetic flux detection means, one word of the output of the magnetic flux detection means The number changes stepwise at each fixed time interval, and as a whole, for example, goes from zero to positive, goes from positive to zero, becomes negative, and returns from negative to zero. The time from the point in time when a current is passed through the conductor of the magnetic flux detection means to the point in time when the output signal of this magnetic flux detection means crosses zero, for example from positive to negative, is determined by the number of points on the position detection plate of the magnetic flux detection means. 1 corresponds to the digit 1 in the direction in which the conducting wires are arranged. Therefore, when this time is counted up, the position of the plurality of conducting wires on the position detection plate of the magnetic flux detection means in the direction in which the conducting wires are arranged is detected.

However, since this position detection device is used in conjunction with a cathode ray tube, and its position detection plate is placed near the cathode ray tube, external magnetic fields such as the deflection magnetic field of the cathode ray tube act on the position detection plate. The magnetic flux detection means detects not only the magnetic flux generated by the current flowing through the conductor of the position detection plate, but also the magnetic flux of this external magnetic field. Therefore, the output signal of the magnetic flux detection means does not actually change as described above during the period in which a constant current is sequentially passed through the plurality of conductors.
The time from the time when a current is first applied to the nearest conductor to the time when the output signal of this magnetic flux detection means crosses zero, for example from positive to negative, is actually This does not correspond to the position in the arrangement direction of the plurality of conductive wires on the board.Therefore, if this time is counted as described above, incorrect position detection will occur in the first place.

OBJECTS OF THE INVENTION In view of this, the present invention provides a method for detecting external magnetic fields such as the deflection magnetic field of the cathode ray tube, when the position detection device used together with the cathode ray tube is configured to magnetically detect the position as described above. This eliminates the influence of the noise and makes accurate position detection possible.

Summary of the Invention The external magnetic field that acts on the position detection plate placed near the cathode ray tube is mainly the deflection magnetic field of the cathode ray tube.The magnetic flux of this deflection magnetic field changes sharply during the horizontal retrace period, but During the scanning period, it changes smoothly and almost linearly. Therefore, the signal component due to the magnetic flux of the external magnetic field, which is included in the output signal of the magnetic flux detection means, has a high frequency during the horizontal retrace period, but has a low frequency close to the horizontal frequency during the horizontal scanning period.

In the present invention, focusing on this point, a constant current is sequentially applied to the plurality of conductors of the position detection plate at constant time intervals in the order of the conductor arrangement during the horizontal scanning period of the cathode ray tube used together. At the same time, the output signal of the magnetic flux detection means is taken out through the band pass filter ff:
During the horizontal scanning period, the low-frequency one-word component due to the magnetic flux of the external magnetic field is removed, and only the high-frequency inertial component due to the magnetic flux generated by the current flowing through the conductor of the position detection plate is obtained. From the point at which a constant current is applied to the first conductor of the plurality of conductors at the beginning of the horizontal scanning period, one of the outputs of the above-mentioned bandpass filter is applied after this point. The time up to the point when the word first crosses a given level in a given orientation is counted and this counted time data is counted)
The position of the plurality of conducting wires on the position detection plate of the magnetic flux detection means in the arrangement direction is detected.

Embodiment FIG. 1 shows an embodiment of the position detecting device of the present invention, and the position detecting plate 10 constituting a tablet board, which is arranged near the cathode ray tube used in combination, is as shown in FIG. A thin transparent insulating plate//Multiple conductive wires Xt, XY...
Xn... are arranged in parallel at regular intervals in the direction O corresponding to the horizontal direction of the screen of the cathode ray tube, and these conductors Xi, X2°"'°Xn-°-' (
A common 1 (connecting conductor Xo is formed at one end of each r, and a plurality of conductors Y / , Y
, 2°゛°°Ym... are arranged in parallel at regular intervals in a direction corresponding to the vertical direction of the screen of the cathode ray tube, and these conductive wires Y/, Y゛° °°Y
m “°°.

A conductive wire YO is formed to commonly connect the insulating plate// to one end of each, and a transparent insulating plate// is also formed on one side and the other side of the insulating plate//.
, 2 and /3 are attached.

The conductor Xo of this position detection plate /θ is connected to the terminal 2/ where the power supply voltage +Vcc is obtained through the resistor Rx, and the conductor X
/, ．． 2.22
...22. When the switches 22, , 222, . . . 22 °"°°° are turned on, the conductor is X/, Xyu...Xn...
A certain power terminal is connected to 2/, and the conductor Y/
＋Y 2°°°°゛Ym...°・The other end constitutes the drive circuit 23, each switch 23/, 232
By turning on the switch 23/, 23.2°--23m--, the resistor Ry is connected to the terminal 2/. Guide 11
i11! Yo'ff: Through conductor Y /+ Y, 2
A constant current flows through the conductor Y t
, Y2...°·°Ym... A magnetic flux is generated around t.

The magnetic flux detection means 30, which constitutes a stylus for drawing figures etc. on the position detection plate 10 which constitutes this tablet board, is composed of a coil, and when placed on the position detection plate /θ, conductors X / , X , 2 . ...Xn...

, Y/+Y, 2, . . . , Ym, etc., a current flows due to electromagnetic induction due to a component of the magnetic flux generated in a direction perpendicular to the surface of the position detection plate 10.

Then, from the clock pulse generation circuit q/, for example, 100
A basic clock pulse CO of R/IHz is obtained, and this clock pulse Co is supplied to a frequency divider circuit q] and is divided by − to obtain a clock pulse qθ pulse C3 of, for example, Ω, 5 MHz. C8 is supplied as a shift pulse to the 7-foot register 2 and -5, respectively.3, while the TV 2, which is provided for the cathode ray tube used in combination,
The horizontal synchronizing signal Hs is taken out from the 37 circuit, and this horizontal synchronizing signal Hs is supplied to the monostable multi-vibration circuit at the terminal 'l3'i A, and as shown in FIG. 3, the horizontal retrace period TR The horizontal scanning period T rises at the leading edge of the horizontal synchronization signal H8 present in
The IN signal HD that falls at the beginning of T is obtained, and this signal H
D is further supplied to the monostable multivibrator 4'5, and the signal E(D rises at the beginning of the horizontal scanning period TT when it falls, and from this, one period of the clock pulse C8 obtained from the frequency divider circuit λ) is obtained. A falling signal Ha is obtained after a certain period of time has elapsed.Then, this signal I-Ic is supplied to the D flip-flop circuit 4 to the D flip-flop circuit 4. The obtained clock pulse Cs is supplied to the clock terminal CK of the circuit tl, and the clock pulse Cs rises immediately after the rise of the signal Hc of the clock pulse Cs, and immediately after the fall of the signal Hc of the clock pulse Cs, from the circuit G The signal ST circuit q'7 K is supplied with a signal that falls at two seconds.
A signal Sx that becomes high level in every second horizontal period and becomes low level in every other horizontal period, and one word Sx.
An inverted f signal Sy is obtained.

Then, the signal ST obtained from the D flip-flop circuit 7 and the signal Sx obtained from the T flip-flop circuit 7 are supplied to the AND gate circuit 7, and one of the signals ST is supplied to the AND gate circuit 7. The signals in every other horizontal period are taken out, and this taken out signal STX is sent to the shift register.
2 as its start pulse. Similarly,
The signal sT obtained from the D flip-flop circuit B and the signal SY obtained from the '1'' flip-flop circuit t17 are supplied to the AND gate circuit G, and the signal ST
The remaining signals in every seventh horizontal period are taken out, and this taken out signal STY is sent to the shift register 2k.
Therefore, in every other horizontal period, within the horizontal scanning period TT, the output terminals N / , Na...Nn... of the shift register 24t are supplied as the start pulse to ..., the third
As indicated by PX in the figure, each clock pulse C8 has a pulse width obtained from the frequency division 'KrtI2.
Pulse signals for one period are sequentially obtained at time intervals corresponding to one period of the clock pulse C8, and this one pulse word is transmitted to the corresponding switch 22t, 22.2 of the drive circuit 22.
...-22n... is supplied to the switch 22
t, 2.22·°...Fi... are turned on in sequence, and the conductors X/, X2...X of the position detection plate 10
.

. . . A constant current flows sequentially at time intervals of one cycle of the clock pulse Cs, and the conductor X t + X 2 .
Magnetic flux surrounding °·Xn゛°°° is generated sequentially.

Similarly, in the remaining every seven horizontal periods, the output terminals My, M, 2, . . ., Mm, . As shown by py as a whole, pulse signals corresponding to one period of the clock pulse C8, each having a pulse width obtained from the frequency dividing circuit '12, are sequentially obtained at time intervals corresponding to one period of the clock pulse C8, and this pulse signal is the corresponding switch of the drive circuit 23, 23/, 23U..., 2
3m... is supplied to the switch, 23/,
23-..., 23m...° are turned on in sequence, and the conductors Y/, Y2...Ym... of the position detection plate 10 are turned on in sequence.
A constant current flows sequentially at intervals of one period of the clock pulse C8 at ...°, and the conductors iWY/, Y2...
・・Ym・・・・・Magnetic flux is generated sequentially around 3°, and in this way, the conductor X / l X, 2.
...Xn... or Y7. Yyu...Y
The magnetic flux detection means 30 detects a component of the magnetic flux generated by the current flowing through m, in a direction perpendicular to the surface of the position detection plate 10. However, as described above, mainly the component of the magnetic flux of the deflection magnetic field of the shadow ray tube in the direction perpendicular to the surface of the position detection plate 10 is also detected. Therefore, one word Ss obtained from the magnetic flux detection means 30 is obtained by adding the signal component SD due to the magnetic flux tζ of the deflection magnetic field to the conductor X.
/ l X J” '・“Xn゛°°°.

Or Y / + Y, 2...Ym...
Signal component S due to magnetic flux generated by current flowing through.

becomes a mixture.

Here, as shown in the top row of FIG. 3, the signal component SD due to the magnetic flux of the deflection magnetic field changes sharply during the horizontal retrace period TR, and is of high frequency (although it is caused by the horizontal scanning period TT).
-''C changes smoothly and almost linearly and becomes a low frequency close to the horizontal frequency.

In addition, the signal 11i, minute So due to the magnetic flux generated when current flows through the conductors X/, X2°°゛°°Xn°°゛°° to Y/, Y coil
As shown in the lower part of FIG. 3, the conduction a X t + X, 2...Xn...
, Y t +Y2 . . . Ym . . . , .
The clock pulse Cs obtained by the above changes in a stepwise manner at each time interval of one cycle, and as a whole, for example, changes from zero to positive, goes from positive to zero, becomes negative, and returns from negative to zero. , at the beginning of the horizontal scanning period TT, the conductor X t +
...Naishi Y/, Yyu...Ym...
From the point at which a constant current is passed through the nearest conductor X/ to Y/, this conductor X / l X s
'“°°.

Xo...or Y/l Y, 2...
, Ym..., the time at which the signal component So due to the magnetic flux generated by the flow of the current crosses zero from positive to negative within the horizontal scanning period TT is every seventh horizontal In the period, magnetic flux detection means 30 at that time
Position detection plate/conductor wire X/, Xyu...Xn...
In the remaining every other horizontal period, the position detection plate 1 of the magnetic flux detection means 30 corresponds to the position of the magnetic flux detection means 30 in the arrangement direction.
0 corresponds to the position in the arrangement direction of the conducting wires Y/, Yyu...Ympa...

Then, the signal SS output from the magnetic flux detection means 30 is supplied to the band pass filter S/. Bandpass filter/
For example, Ω,,tMH2, which is sufficiently higher than the horizontal frequency and is the frequency of the clock pulse C8 obtained from the frequency divider circuit Guco.
It has a single peak characteristic that extracts a signal component at a constant frequency sufficiently lower than , for example, θOkH2. Therefore, from this bandpass filter S/, in the horizontal scanning period TT,
The signal component SD due to the magnetic flux of the deflection value W is removed and the conductor wires X/X2...Xn... or Y/,
Yyu... Ymo "00 of the signal component SO due to the magnetic flux generated by the current flowing in °°°
Only the signal component of kH2 is extracted.

The output signal S of this bandpass filter S/ is applied to the voltage comparator circuit constituting the zero loss detection circuit, so that the signal sn becomes positive as shown in the lower part of Fig. 3. The signal Sz falls to 9 when the signal SB crosses zero from negative to positive, and rises when the signal SB crosses zero completely from negative to positive.
is obtained. Then, the signal ST obtained from the D flip-flop circuit 3 is the left 3 of the RS flip-flop circuit.
The signal Sz obtained from the voltage comparator circuit 5.2 is supplied to the reset terminal R of the circuit S3. Conductor X / , X , ;r ””'X
n...or Y/+Y 2...Yr
n...σ) The nearest conductor X/or Y/
When a constant current is applied to the 1st word ST, the output of the bandpass filter S/100 SB changes from negative to positive for the first time within the horizontal scanning period TT. A signal Gc is obtained which falls at the first rise indicated by an upward arrow in FIG. 3 within the horizontal scanning period TT of the signal Sz, which is the point in time when the signal Sz crosses zero toward .

Here, the point in time when the signal SB of the output of the bandpass filter S/ first crosses zero from negative to positive within the horizontal scanning period TT is the point at which the signal SB of the output of the magnetic flux detection means 30, Signal component So due to the magnetic flux generated by the current flowing through /,
1, which corresponds to the point in time when GC crosses zero from positive to negative, and is delayed by a certain period of time from this point. Therefore, from the rising edge 9 to the falling edge 1 of the signal GC obtained from the RS flip-flop circuit S3, In every seventh horizontal period, the time is determined by the position detection plate 10 of the magnetic flux detection means 30 at that time.
Corresponding to the position in the arrangement direction of the second conducting wire X/, X2... This corresponds to the position in the arrangement direction of the upper conducting wires Y i + Y, 2...Ym...

Then, the clock pulse generation circuit 11. The 700 MHz clock pulse Co obtained from / and one word Gc obtained from the RS flip-flop circuit S3 are supplied to the AND gate circuit 5 The conductor wire X t + X on the position detection plate 10 of the magnetic flux detection means 30 when CO is
2...Xn...or Y, 1Y, 2...
...Ym... The number corresponding to the position in the arrangement direction is extracted. On the other hand, the horizontal synchronization 1 word Hs is supplied to the counter S5σ) clear terminal CL R through the terminal 3, and the horizontal synchronization signal HS present in the horizontal retrace period TR is
At the leading edge of the counter, S-5 is cleared, and after this clearing σ) the RS flip-flop circuit S3 within the horizontal scanning period TT f)? 4J, during the period when the signal GC is at the no-y level, the AND gate circuit, t4
The resulting clock pulse Cc is supplied to the clock terminal CK of the counter 55 and is counted.

Therefore, the data DE output from the counter IS- is 1
From the fall of the signal GC obtained from the left 3 RS flip-flop circuit in the middle of the horizontal scanning period TT of the second horizontal period, the horizontal synchronizing signal Hs within the next horizontal retrace period Ta
During the period up to the leading edge of , the conductor wires X/,
The content shows all the positions in the array direction, and the remaining 1
From the falling edge of the signal Gc obtained from the RS flip/flurograph circuit VW5 in the middle of the horizontal scanning period TT of the second horizontal period, the horizontal synchronizing signal + in the next horizontal retrace period TR is
During the period at the leading edge trench of jH8, the conductor wire Y7°Y, 2... on the position detection plate 10 of the magnetic flux detection means 30 at that time
Contents indicating the position in the arrangement direction of Ym... (C becomes 1
In addition, the horizontal synchronizing signal Hs is supplied to the reset terminal R of the free-lag frog circuit S through the terminal 3f, and the signal SZ obtained from the voltage comparator circuit 32 is supplied to the set terminal S of the circuit S. With the supply type t, the data DE of the output of the counter ss is set to 14X/, X, 2...Xn... on the position detection plate 10 of the magnetic flux detection means 3o.
・・・Naishi Y / , Yyu・・°゛・Ymo“°°°
A signal DA that becomes high level is obtained during a period in which the content indicates the position in the arrangement direction.

Then, the conductor X t on the position detection plate 10 of the magnetic flux detection means 3o obtained by the T flip frog circuit l17
, X 2...Mountain X. The horizontal period during which the position in the arrangement direction of ... is detected and the conducting wires Y t , Y 2 ...°...
A signal Sx to SY that distinguishes the entire horizontal period in which the position in the array direction of Ym°°°°゛ is detected, and the counter 3, ! The output data Dg and the output data DE of the counter 3 obtained from the Rs flip-frog circuit S are the second lead of the position detection plate 10 of the magnetic flux detection means 3o.
t + X 2”'...Xn1003. or Yt, Y
A signal DA distinguishing between a period in which the content indicates the position of the mountain in the arrangement direction and other periods is supplied to the data processing circuit s7, and r=J road S road 7 , the conductor wires X/, XY on the position detection plate 10 of the magnetic flux detection means 3o.
...Xn...Mountain arrangement direction and conducting wire Y/, Y
, 2...Ym...Data output Do indicating the position of the mountain in the arrangement direction is obtained.

Effects of the Invention According to the position detection device of the present invention, the conductor X of the position detection plate 10 within the horizontal scanning period TT of the cathode ray tube used
t, Xyu mountain...Xn...mountain or Yt, Y2°゛°
“A constant current flows through the Ym° mountain at constant time intervals in the order of the arrangement of the conductors, and the magnetic flux detecting means 3
One word of the output of o is taken out through the bandpass filter /'f:, so that during the horizontal scanning period Tr, low frequency signals due to the magnetic flux of an external magnetic field such as the deflection magnetic field of the cathode ray tube used together are detected. j Extraneous components are removed and current flows through 4hlX,,X2°°゛°Xn・°゛°° or Y/r Y2...Ym... Only one component of high frequency due to the magnetic flux generated by is obtained, and at the beginning of the horizontal scanning period TT, the conductor X t ,
... or Yt.

From the point in time when a constant current is passed through the conductor X/ or Yt of the -deceased limb of Y, 2...Ym..., after this point, the output of the band-pass filter left/ The time at time 1 when the signal SB first crosses a predetermined level in a predetermined direction is determined by the conductor X t +
/ + Y 2°°・°°Ym・°°P This corresponds accurately to the position in the arrangement direction, and by counting this time, it can be used in combination with the external magnetic field such as the deflection magnetic field of the cathode tube. The position is accurately detected without being affected.

[Brief explanation of the drawing]

FIG. 7 is a connection diagram showing one embodiment of the position detection device of the present invention, FIG. 2 is a sectional view of a part of an example of the position detection plate, and FIG.
The figure is a waveform diagram for explaining the operation of the apparatus of FIG. 1. In the figure, 10 is a position detection plate, X / r X 2"°...
・Xn...and Y/, Y, 2...
Ym... is the conductor, 2.2 and 23 are the drive circuits, 2'! and 231rJ-shift register, 30
is a magnetic flux detection means, lI/ is a clock pulse generation circuit, 4
'l is a frequency dividing circuit, Hs is a horizontal synchronizing signal, lI and 45
is a monostable multivibrator, <71. ldD flip-flop circuit, 1117 is a T flip-flop circuit, 5/ is a band pass filter, 3Ω is a voltage comparison circuit, 33
and 3 are I-S flip frog circuits 1.5"51
-, J: counter, S7 is a data processing circuit.

Claims (1)

[Claims] A position detection plate in which a plurality of conductive wires are arranged in parallel at regular intervals and a cathode ray tube used in combination with a horizontal scanning period of 1/? : , a circuit that sequentially passes a constant current through the plurality of conductors at regular intervals in the order of their arrangement, and a current flowing through the conductors when placed on the position detection board. a magnetic flux detecting means for detecting the magnetic flux to be converted into an electrical signal, and a band for extracting a signal component of a constant frequency sufficiently higher than the horizontal frequency of the cathode ray tube used together from the output signal of the magnetic flux detecting means. a pass filter, and one word of the output of the band pass filter from the time when a constant current is applied to the first conductor of the plurality of conductors at the beginning of the horizontal scanning period; a circuit that counts the time until the point when the signal first crosses a predetermined level in a predetermined direction; and a circuit that counts the time until the point when the signal first crosses a predetermined level in a predetermined direction; A position detection device that detects